Methods and apparatus for adaptive channel access

ABSTRACT

A communication device determines, in connection with a prior uplink multi-user (UL MU) communication in which the communication device participated, whether the communication device is to use one or more first channel access parameters, or one or more second channel access parameters for accessing a communication medium for a single user (SU) transmission by the communication device, where using the one or more first channel access parameters is associated with a greater probability of obtaining access to the communication medium as compared to using the one or more second channel access parameters. Depending on the determination made, the communication device uses the one or more first channel access parameters, or the one or more second channel access parameters to attempt to access the communication medium. In response to accessing the communication medium, the communication device transmits the SU transmission via the communication medium.

CROSS REFERENCES TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication No. 62/290,184, entitled “Adaptive EDCA Rules for ChannelAccess In 11ax,” filed on Feb. 2, 2016, which is hereby expresslyincorporated herein by reference in its entirety.

FIELD OF TECHNOLOGY

The present disclosure relates generally to communication systems and,more particularly, to wireless local area networks that utilizemulti-user transmissions.

BACKGROUND

Wireless local area networks (WLANs) have evolved rapidly over the pastdecade. Development of WLAN standards such as the Institute forElectrical and Electronics Engineers (IEEE) 802.11a, 802.11b, 802.11g,802.11n, and 802.11ac Standards has improved single-user peak datathroughput. For example, the IEEE 802.11b Standard specifies asingle-user peak throughput of 11 megabits per second (Mbps), the IEEE802.11a and 802.11g Standards specify a single-user peak throughput of54 Mbps, the IEEE 802.11n Standard specifies a single-user peakthroughput of 600 Mbps, and the IEEE 802.11 ac Standard specifies asingle-user peak throughput in the gigabits per second (Gbps) range.Future standards promise to provide even greater throughputs, such asthroughputs in the tens of Gbps range.

SUMMARY

In an embodiment, a method includes: determining, at a communicationdevice and in connection with a prior uplink multi-user (UL MU)communication in which the communication device participated, whetherthe communication device is to use i) one or more first channel accessparameters or ii) one or more second channel access parameters foraccessing a communication medium for a single user (SU) transmission bythe communication device, wherein using the one or more first channelaccess parameters is associated with a greater probability of obtainingaccess to the communication medium as compared to using the one or moresecond channel access parameters; in response to determining that thecommunication device is to use the one or more first channel accessparameters, using, at the communication device, the one or more firstchannel access parameters to attempt to access the communication medium;in response to determining that the communication device is to use theone or more second channel access parameters, using, at thecommunication device, the one or more second channel access parametersto attempt to access the communication medium; and in response toaccessing the communication medium, transmitting, with the communicationdevice, the SU transmission via the communication medium.

In another embodiment, an apparatus comprises a network interface deviceassociated with a communication device, the network interface devicehaving one or more integrated circuit devices. The network interfacedevice comprises a media access control (MAC) processor implemented onthe one or more integrated circuit devices. The MAC processor includes alogic circuit implemented on the one or more integrated circuit devices,and the logic circuit is configured to: determine, in connection with aprior uplink multi-user (UL MU) communication in which the communicationdevice participated, whether the network interface device is to use i)one or more first channel access parameters or ii) one or more secondchannel access parameters for accessing a communication medium for asingle user (SU) transmission by the communication device, wherein usingthe one or more first channel access parameters is associated with agreater probability of obtaining access to the communication medium ascompared to using the one or more second channel access parameters. Theone or more integrated circuit devices are configured to: in response todetermining that the communication device is to use the one or morefirst channel access parameters, use the one or more first channelaccess parameters to attempt to access the communication medium; inresponse to determining that the communication device is to use the oneor more second channel access parameters, use the one or more secondchannel access parameters to attempt to access the communication medium;and in response to accessing the communication medium, prompt thecommunication device to transmit the SU transmission via thecommunication medium.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an example wireless local area network(WLAN), according to an embodiment of the present disclosure.

FIG. 2 is a diagram of an example transmission sequence corresponding toan uplink multi-user communication in a WLAN, according to an embodimentof the present disclosure.

FIG. 3 is a diagram of another example transmission sequence in a WLAN,according to an embodiment of the present disclosure.

FIG. 4 is a flow diagram of an example method for communicating in awireless communication network, according to an embodiment of thepresent disclosure.

FIG. 5 is a flow diagram of an example method for determining one ormore channel access parameters to utilize, according to an embodiment ofthe present disclosure.

FIG. 6 is a flow diagram of another example method for determining oneor more channel access parameters to utilize, according to an embodimentof the present disclosure.

DETAILED DESCRIPTION

Channel access techniques described below are discussed in the contextof wireless local area networks (WLANs) that utilize protocols the sameas or similar to protocols defined by the 802.11 Standard (and/or futureversions of the 802.11 Standard) from the Institute of Electrical andElectronics Engineers (IEEE) merely for explanatory purposes. In otherembodiments, however, channel access techniques are utilized in othertypes of wireless communication systems (e.g., a wireless wide areanetwork (WWAN), a cellular network, a wireless metropolitan area network(WMAN), a wireless personal area network (WPAN), etc.).

The IEEE 802.11 ax Standard (still in development), also known asHigh-Efficiency Wireless (HEW), is an amendment to the IEEE 802.11Standard. The IEEE 802.11ax Standard aims to improve the averagethroughput per user by up to four times in high-density environments.One of the features permitted by the IEEE 802.11 ax Standard is anuplink multi-user (UL MU) transmission, which involves simultaneoustransmission of data from multiple client stations to an access point(AP). An UL MU transmission reduces collisions and improves spectrumefficiency. UL MU transmissions are prompted by a trigger frame from theAP. In some embodiments, in response to receiving a trigger frame, aclient station disregards single user transmission channel accessprocedures (e.g., enhanced distributed channel access (EDCA) procedures,as defined by the IEEE 802.11 Standard), and begins transmitting as partof an UL MU transmission.

In some embodiments, a WLAN includes both i) client stations that areconfigured to participate in UL MU transmissions (e.g., IEEE 802.11 axcompatible client stations), and ii) one or more legacy client stations(e.g., client stations that are configured to operate according to oneor more earlier versions of the IEEE 802.11 Standard) that are notconfigured to participate in UL MU transmissions. If the IEEE 802.11axcompatible client stations and the legacy client stations both use thesame channel access parameters (e.g., the same EDCA parameters, the samebackoff parameters, the same contention window parameters, etc.), thismay lead to channel access unfairness in that the IEEE 802.11axcompatible client stations will be provided more access to the channelmedium, as compared to legacy client stations, as a result of UL MUtransmissions that disregard the channel access parameters.

In one or more embodiments described herein, a wireless network devicesuch as an AP of a WLAN transmits data streams to one or more clientstations. The AP is configured to operate with client stations accordingto at least a first communication protocol. The first communicationprotocol is sometimes referred to herein as “high efficiency WiFi,”“HEW” communication protocol, “HE” communication protocol, or IEEE802.11ax communication protocol. In some embodiments, the firstcommunication protocol supports orthogonal frequency divisionmultiplexing (OFDM) communication in both downlink direction from the APto a client station and uplink direction from a client station to theAP. In an embodiment, the first communication protocol supports a singleuser (SU) mode in which each client station transmits a data stream to,or receives a data stream from, the AP one at a time once the clientstation (e.g., for UL single user (SU) transmissions), or the AP (e.g.,for downlink single user (DL SU) transmissions), secures access to themedium by performing a channel access procedure (e.g., an EDCA procedurereferred to in the IEEE 802.11 Standard or a similar procedure).

In some embodiments, the first communication protocol also supports oneor more multi-user (MU) modes in which the AP transmits multipleindependent data streams simultaneously to multiple client stations, orreceives independent data streams simultaneously transmitted by multipleclient stations. Multi-user transmission to, or by, multiple clientstations is performed using MU multiple-input multiple-output (MU-MIMO)transmission, in which respective spatial streams are used fortransmission to, or by, respective ones of the multiple client stations,and/or using orthogonal frequency division multiple access (OFDMA)transmission, in which respective frequency sub-channels of acommunication channel are used for simultaneous transmission to, or by,respective ones of the multiple client stations, in various embodiments.

To improve fairness among client stations in gaining access to thecommunication channel, a client station configured to operate accordingto the first communication protocol uses adaptive channel accessparameters (e.g., EDCA parameters, backoff parameters, contention windowparameters, etc.) that vary depending on a current situation in whichthe client station is operating, according to some embodiments. Forexample, in at least one embodiment, a client station configured tooperate according to the first communication protocol uses one or morelegacy channel access parameters in some situations, and uses different(e.g., non-legacy) one or more channel access parameters in othersituations. According to an embodiment, the one or more legacy channelaccess parameters give the client station the same chance of gainingaccess to the channel as legacy client stations, while the one or moredifferent channel access parameters give the client station a smallerchance of gaining access to the channel than legacy client stations(e.g., the different channel access parameters correspond to generallylonger backoff periods, generally longer contention windows, increasedchances of setting longer backoff periods, etc., as compared to thelegacy channel access parameters). In another embodiment, the chance togain access to the channel differs between the client station and legacyclient stations in various other ways depending on whether the legacychannel access parameters or the different channel access parameters areused.

In some embodiments, adaptive channel access parameters (e.g., EDCAparameters, backoff parameters, contention window parameters, etc.) varydepending on a current situation related to uplink multiusertransmissions. For example, in some embodiments, adaptive channel accessparameters used by a client station vary depending on whether the clientstation has successfully completed an uplink transmission as part of anuplink multiuser transmission. As another example, in some embodiments,adaptive channel access parameters used by a client station varydepending on a length of time since the client station successfullycompleted an uplink transmission as part of an uplink multiusertransmission. As yet another example, in some embodiments, adaptivechannel access parameters used by a client station vary depending on alength of time the client station has been attempting to access achannel medium since successfully completing an uplink transmission aspart of an uplink multiuser transmission.

FIG. 1 is a block diagram of an example wireless local area network(WLAN) 10, according to an embodiment. The WLAN 10 supports downlink(DL) and uplink (UL) multiuser (MU) communication between an accesspoint (AP) and a plurality of client stations. It should be noted thatwhile one WLAN 10 is depicted in FIG. 1, this is only intended to beillustrative, and any suitable number of WLANs may be present.

In an embodiment, the WLAN includes at least one access point (AP) 14.The configuration of the AP 14 varies among different embodiments, but atypical configuration will now be described, using AP 14 as an example.The AP 14 includes a host processor 15 coupled to a network interfacedevice 16. The network interface device 16 includes a medium accesscontrol (MAC) processor 18 and a physical layer (PHY) processor 20. ThePHY processor 20 includes a plurality of transceivers 21, and thetransceivers 21 are coupled to a plurality of antennas 24. Althoughthree transceivers 21 and three antennas 24 are illustrated in FIG. 1,in one or more embodiments the AP 14 includes other suitable numbers(e.g., 1, 2, 4, 5, etc.) of transceivers 21 and/or antennas 24. AlthoughAP 14 includes the same number of antennas 24 and transceivers 21, insome embodiments the AP 14 includes a different number of antennas 24than transceivers 21, and antenna switching techniques are utilized.

In an embodiment, the network interface device 16 includes a wiredcommunication interface for exchanging one or more of i) communicationprotocol data units (e.g., Internet protocol (IP) packets, transmissioncontrol protocol (TCP) packets, etc.), ii) wireless network managementparameters, iii) wireless network status information, etc., with thehost processor 15.

In an embodiment, the MAC processor 18 and the PHY processor 20 includerespective wired communication interfaces configured to exchange one ormore of i) communication protocol data units (e.g., MAC layer servicedata units (MSDUs), PHY service data units (PSDUs), etc.), ii) wirelessnetwork management information, iii) wireless network statusinformation, etc., between the MAC processor 18 and the PHY processor20. In an embodiment, the wired communication interface of the MACprocessor 18 is coupled to the wired communication interface of the PHYprocessor 20.

In some embodiments, the one or more transceivers 21 include radiofrequency (RF) circuitry configured to upconvert baseband signalsgenerated by baseband transmit components the PHY processor 20 to RFsignals for wireless transmission via the one or more antennas 24. Insome embodiments, the one or more transceivers 21 include RF circuitryfor downconverting RF signals wirelessly received via the one or moreantennas 24 to baseband signals for processing by baseband receivecomponents of the PHY processor 20.

In one or more embodiments, the network interface device 16 isimplemented on one or more integrated circuit (IC) devices configured tooperate as described below. For example, in an embodiment, at least aportion of the MAC processing unit 18 is implemented on a first ICdevice and at least a portion of the PHY processing unit 20 isimplemented on a second IC device. As another example, at least aportion of the MAC processing unit 18 and at least a portion of the PHYprocessing unit 20 are implemented on a single IC device, according toan embodiment.

In an embodiment, baseband transmit components of the PHY processor 20,baseband receive components of the PHY processor 20, and the one or moretransceivers 21 are implemented on a single IC.

In another embodiment, baseband transmit components of the PHY processor20 and baseband receive components of the PHY processor 20 areimplemented on a first IC, and the one or more transceivers 21 areimplemented on a second IC. In such an embodiment, the first IC and thesecond IC include respective wired communication interfaces configuredto exchange i) baseband signals corresponding to signals for wirelesstransmission via the one or more antennas 24, and ii) baseband signalscorresponding to signals wireless received via the one or more antennas24, between the first IC and the second IC. In an embodiment, the wiredcommunication interface of the first IC is coupled to the wiredcommunication interface of the second IC.

In some embodiments, the MAC processor 18 and/or the PHY processor 20are configured to operate according to a first communication protocol(e.g., a High Efficiency, HE, or 802.11ax communication protocol) thatsupports UL MU transmissions. In some embodiments, the MAC processor 18and/or the PHY processor 20 are also configured to operate according toone or more second communication protocols, such as a “legacy” protocolthat does not support UL MU transmissions (e.g., according to the IEEE802.11n Standard and/or the IEEE 802.11ac Standard).

The WLAN 10 includes a plurality of client stations 25. Although fourclient stations (25-1, 25-2, 25-3, and 25-4) are illustrated in FIG. 1,in various scenarios and embodiments the WLAN 10 includes other suitablenumbers (e.g., 1, 3, 4, 5, 6, etc.) of client stations 25. Theconfiguration of the client station 25 varies among differentembodiments, but a typical configuration will now be described usingclient station 25-1 as an example. The client station 25-1 includes ahost processor 26 coupled to a network interface device 27. In anembodiment, the network interface device 27 includes one or more ICsconfigured to operate as described below. The network interface device27 includes a MAC processor 28 and a PHY processor 29. The PHY processor29 includes a plurality of transceivers 30, and the transceivers 30 arecoupled to a plurality of antennas 34. Although three transceivers 30and three antennas 34 are illustrated in FIG. 1, in one or moreembodiments the client station 25-1 includes other suitable numbers(e.g., 1, 2, 4, 5, etc.) of transceivers 30 and/or antennas 34. Althoughthe client station 25-1 includes the same number of antennas 34 andtransceivers 30, in some embodiments the client station 25-1 includes adifferent number of antennas 34 than transceivers 30, and antennaswitching techniques are utilized.

In one or more embodiments, the network interface device 27 isimplemented on one or more IC devices. For example, in an embodiment, atleast a portion of the MAC processor 28 is implemented on at least afirst IC device, and at least a portion of the PHY processor 29 isimplemented on at least a second IC device. In another embodiment, atleast a portion of the MAC processor 28 and at least a portion of thePHY processor 29 are implemented on a single IC device.

In some embodiments, the network interface 27 (e.g., the MAC processingunit 29 and the PHY processing unit 30) of the client station 25-1 isconfigured to operate according to the first communication protocol. Insome embodiments, the network interface 27 (e.g., the MAC processingunit 29 and the PHY processing unit 30) is also configured to operateaccording to one or more second communication protocols.

In an embodiment, one or more of the client stations 25-2, 25-3, and25-4 has a structure that is the same as or similar to the clientstation 25-1. In these embodiments, the one or more client stations 25structured the same as or similar to the client station 25-1 has thesame or a different number of transceivers and antennas. For example,the client station 25-2 has only two transceivers and two antennas (notshown), according to an embodiment.

In an embodiment, the client station 25-4 is not configured toparticipate in UL MU transmissions, e.g., the client station 25-4 isconfigured to operate according to one or more second communicationprotocols, such as a “legacy” protocol that does not support UL MUtransmissions (e.g., according to the IEEE 802.11n Standard and/or theIEEE 802.11 ac Standard), but is not configured to operate according tothe first communication protocol that supports UL MU transmissions.Client stations that are not configured to participate in UL MUtransmissions are sometimes referred to herein as “legacy clientstations”. Client stations that are configured to participate in UL MUtransmissions are sometimes referred to herein as “non-legacy clientstations”.

In various embodiments, the MAC processor 18 of the AP 14 is configuredto perform MAC functions defined by the first communication protocol,and the PHY processor 20 is configured to perform PHY functions definedby the first communication protocol. For example, in one or moreembodiments, the MAC processor 18 and/or the PHY processor 20 of the AP14 are configured to generate data units conforming to the firstcommunication protocol and having formats described herein. In anembodiment, the MAC processor 18 of the AP 14 is configured to generateMAC layer service data units (e.g., MSDUs) such as data frames, controlframes, etc., and provide at least some of the MSDUs to the PHYprocessor 20 of the AP 14. In some embodiments, the PHY processor 20 isconfigured to receive MAC layer data units (e.g., MSDUs) from the MACprocessor 18 and encapsulate the MAC layer data units to generate PHYdata units such as PHY protocol data units (PPDUs) for transmission viathe antennas 24. Similarly, in an embodiment, the PHY processor 20 isconfigured to receive PHY data units that were received via the antennas24, and extract MAC layer data units encapsulated within the receivedPHY data units. In an embodiment, the PHY processor 20 provides theextracted MAC layer data units to the MAC processor 18, which processesthe MAC layer data units.

The transceiver(s) 21 is/are configured to transmit the generated dataunits via the antenna(s) 24. Similarly, the transceiver(s) 21 is/areconfigured to receive data units via the antenna(s) 24. In someembodiments, the MAC processor 18 and/or the PHY processor 20 of the AP14 are configured to process a received data unit conforming to thefirst communication protocol and having a format described hereinafter,and to determine that such a data unit conforms to the firstcommunication protocol, according to various embodiments.

In one or more embodiments, the MAC processor 28 of the client device25-1 is configured to perform MAC functions defined by the firstcommunication protocol, and the PHY processor 29 is configured toperform PHY functions defined by the first communication protocol. Forexample, in various embodiments, the MAC processor 28 and/or the PHYprocessor 29 of the client device 25-1 are configured to generate dataunits conforming to the first communication protocol and having formatsdescribed herein. For example, in an embodiment, the MAC processor 28 isconfigured to generate MAC layer service data units (e.g., MSDUs) suchas data frames, control frames, etc., and provide at least some of theMSDUs to the PHY processor 29. In an embodiment, the PHY processor 29 isconfigured to receive MAC layer data units (e.g., MSDUs) from the MACprocessor 28 and encapsulate the MAC layer data units to generate PHYdata units such as PPDUs for transmission via the antennas 34.Similarly, in an embodiment, the PHY processor 29 is configured toreceive PHY data units that were received via the antennas 34, andextract MAC layer data units encapsulated within the received PHY dataunits. In an embodiment, the PHY processor 29 provides the extracted MAClayer data units to the MAC processor 28, which processes the MAC layerdata units.

The transceiver(s) 30 is/are configured to transmit the generated dataunits via the antenna(s) 34. Similarly, the transceiver(s) 30 is/areconfigured to receive data units via the antenna(s) 34. In someembodiments, the MAC processor 28 and/or the PHY processor 29 of theclient device 25-1 are configured to process a received data unitconforming to the first communication protocol and having a formatdescribed herein, and to determine that such a data unit conforms to thefirst communication protocol, according to various embodiments.

In an embodiment, the AP 14 is configured to operate according to awireless communication protocol that utilizes Orthogonal FrequencyMultiple Division Access (OFDMA) technology and/or multi-usermultiple-input, multiple-output (MU-MIMO) technology.

In an embodiment, the MAC processor 28 includes a logic circuit 50configured to determine whether the network interface device 27 (e.g.,the MAC processor 28) is to use i) one or more first channel accessparameters or ii) one or more second channel access parameters foraccessing a communication medium corresponding to the network 10.Various techniques for determining whether the network interface device27 is to use i) the one or more first channel access parameters or ii)the one or more second channel access parameters, according to variousembodiments, are discussed in more detail below.

In some embodiments, the MAC processor 28 further includes one or morecounter circuits 54 (referred to herein as “counters”) coupled to, orincluded in, the logic circuit 50. In some embodiments, the logiccircuit 50 uses the one or more counters 54, at least in some scenarios,to determine whether the network interface device 27 is to use i) theone or more first channel access parameters or ii) the one or moresecond channel access parameters. Various techniques for using one ormore counters 54 in connection with determining whether the networkinterface device 27 is to use i) the one or more first channel accessparameters or ii) the one or more second channel access parameters,according to various embodiments, are discussed in more detail below. Inan embodiment, the one or more counters 54 are, or include, timercircuits (referred to herein as “counters”). In an embodiment, the oneor more counters 54 are separate than any backoff counters included inand/or utilized by the network interface device 27.

In an embodiment, the logic circuit 50 includes a hardware statemachine. In an embodiment, the network interface device 27 and/or theMAC processor 28 includes a processor coupled to a memory that storesmachine readable instructions, where the processor is configured toexecute the machine readable instructions stored in the memory; in anembodiment, the logic circuit 50 is included in the processor, andfunctionality of the logic circuit 50 is implemented by the processorexecuting machine readable instructions stored in the memory.

FIG. 2 is a diagram of an example UL MU transmission sequence 400 in aWLAN, such as the WLAN 10 of FIG. 1, according to an embodiment. In theexample transmission sequence 400, an AP (e.g., AP 14 in the examplenetwork 10 shown in FIG. 1) triggers a UL MU transmission (e.g., an ULOFDMA transmission) by multiple non-legacy client stations, such asmultiple ones of the non-legacy client stations 25, during atransmission opportunity period (TXOP) 402.

Beginning at a time t1, the AP 14 transmits a trigger frame 404 to aplurality of client stations (e.g., client stations 25-1, 25-2, and 25-3in the example network 10 shown in FIG. 1). In an embodiment, the TXOP402 is obtained by (e.g., based on a suitable channel assessmentprocedure, such as a carrier sense multiple access with collisionavoidance (CSMA/CA) procedure, a backoff procedure, etc.), or scheduledfor, the AP 14.

In an embodiment, the trigger frame 404 is included in a physical layerconvergence protocol (PLCP) data unit (PPDU). In an embodiment and/orscenario, the trigger frame 404 is duplicated in each channel (e.g., ineach 20 MHz channel) of the entire bandwidth of the TXOP 402. In anembodiment in which the trigger frame 404 is included in a legacy PPDUthat is duplicated in each channel (e.g., in each 20 MHz channel) of theentire bandwidth of the TXOP 402, the communication medium is protectedfrom interference by any device in the network over the entire bandwidthof the TXOP 402, at least for the duration defined by a duration fieldof the trigger frame 404, or for the duration of the entire TXOP 402. Inanother embodiment and/or scenario, the trigger frame 404 occupies theentire bandwidth of the TXOP 402, for example, when each of the clientstations 25 to which the trigger frame 404 is transmitted is capable ofoperating in the entire bandwidth of the TXOP 402. In an embodiment, atrigger frame that occupies the entire bandwidth of the TXOP 402 isrelatively shorter, and accordingly is transmitted in a relativelyshorter time period, as compared to a trigger frame that is duplicatedin each narrowest channel bandwidth of the TXOP 402.

In accordance with an embodiment, time t2 at each non-legacy clientstation 25 participating in the UL MU transmission begins uponexpiration of a predetermined time interval, such as for example a timeinterval corresponding to a short inter-frame space (SIFS) defined bythe IEEE 802.11 Standard or another suitable predetermined timeinterval, after completion of reception of the trigger frame 404 at theclient station 25. In another embodiment, a predetermined time periodthat is greater than SIFS is defined, and time t2 at each client station25 begins upon expiration of a predetermined time interval correspondingto the predetermined time interval greater than SIFS. For example, apredetermined time period that is greater than SIFS and less than apoint coordination function (PCF) interframe space (PIFS), as defined bythe IEEE 802.11 Standard, is utilized. The greater predetermined timeinterval may provide sufficient time for the client stations 25 todecode the trigger frame 404 and to prepare for uplink transmissionbased on the uplink scheduling information provided by the trigger frame404, in at least some embodiments.

In an embodiment, each client station begins transmission of arespective OFDM data unit 406 at the time t2 in a respectivesub-channel, allocated to the client station. In other embodiments, eachof at least some of the client stations begins transmission of arespective OFDM data unit 406 at the time t2 in across multiplesub-channels using MU MIMO techniques.

At a time t3, the AP (e.g., AP 14 in the example network 10 shown inFIG. 1) begins transmission of respective acknowledgement (ACK) frames410 to the client stations 25 (STA1 through STA3) acknowledging receiptof the OFDM data units 406 from the client stations 25. In anotherembodiment, the AP 14 transmits a broadcast acknowledgement frame thatincludes respective acknowledgements for the client stations 25 (STA1through STA3). In at least one embodiment, time t3 begins uponexpiration of a predetermined time interval, such as, for example, atime interval corresponding to SIFS, after completion of reception ofthe UL MU transmission 408 at the AP 14. In an embodiment, the AP 14transmits the ACK frames 410 to the client stations 25, as parts of anOFDMA transmission to the client stations 25, in the respectivesub-channels allocated to the client stations 25 as indicated in thetrigger frame 404. In another embodiment, the ACK 410, or a portion ofthe ACK 410, is a MU MIMO transmission that spans multiple sub-channels.

In an embodiment, non-legacy client stations are also configured toutilize UL SU transmissions. For example, in some scenarios, anon-legacy client station will choose not to wait until a next triggerframe from the AP to conduct an UL transmission, and instead willattempt to gain access to the communication medium and transmit an UL SUtransmission. This may occur, for example, when the non-legacy clientstation has a large volume of data to transmit and/or has a highpriority transmission. When attempting to gain access to thecommunication medium for an UL SU transmission, these client stationsoften will be competing with legacy client stations and other non-legacyclient stations.

In one or more embodiments, the AP and the client stations (e.g., AP 14and client stations 25 in the example network 10 shown in FIG. 1)contend for communication medium using carrier sense multiple accesswith collision avoidance (CSMA/CA) protocol or another suitable mediumaccess protocol. In an embodiment, the AP and the client stationsimplement a clear channel assessment (CCA) procedure, in which theAP/client station determines the energy level of the medium in order todetermine whether the medium is busy or idle. If the medium is idle, thedevice can count down a backoff counter. If the backoff counter reachesa predetermined number (e.g., 0), the device can transmit. If the mediumbecomes busy, the device pauses the backoff counter and waits until themedium becomes idle again, and then continues counting down the backoffcounter while the medium is idle.

In some embodiments, the backoff counter is initialized with a valuedetermined based on a parameter such as a contention window (CW)parameter. For example, in an embodiment, the initial value of thebackoff counter is randomly, or pseudo-randomly, chosen as a valuebetween 0 and CW. If a client station determines that a collision withits transmission occurred, the client station will double CW, choose avalue for the backoff counter as a value between 0 and CW, and restartthe backoff counter. This procedure continues (up to a maximum value ofCW (CW_(max))). When the client station determines that it hassuccessfully completed a transmission, the client station resets CW to aminimum of initial value of CW (CW_(min)).

If the CW_(min) parameter is increased, the backoff period (as measuredby the backoff counter) tends to increase. If a first backoff periodutilized by a first client station is longer than a second backoffperiod utilized by a second client station, the first client stationwill tend to have more difficulty obtaining access to a channel mediumas compared to the second client station. Thus, in an embodiment,increasing the CW_(min) parameter utilized by a station tends toincrease the difficulty of obtaining access to a channel medium whenother stations are utilizing a smaller CW_(min) parameter.

Non-legacy client stations will often be competing with legacy clientstations when attempting to gain access to the communication medium foran UL SU transmission. Thus, the non-legacy client stations will beutilizing a backoff counter, a CSMA/CA protocol, etc. in a mannersimilar to the legacy client stations when attempting to gain access tothe communication medium for an UL SU transmission, according to atleast some embodiments.

For UL MU transmissions, however, the non-legacy client stations willdisregard any backoff counters, CSMA/CA protocols, etc., and insteadwill simply begin transmitting a predetermined time period after an endof the trigger frame from the AP, according to some embodiments.

In some embodiments, a non-legacy client station (e.g., client station25-1) selectively utilizes a first set of channel access parameters or asecond set of channel access parameters (also referred to herein simplyas “first channel access parameters” and “second channel accessparameters”) for initiating transmission of an UL SU data unit. In anembodiment, the first and second channel access parameters includebackoff parameters (e.g., CW parameters). In an embodiment, thenon-legacy client station uses the first channel access parameters insome situations, and uses the second channel access parameters in othersituations, where the first channel access parameters are different fromthe second channel access parameters. The first channel accessparameters are sometimes referred to herein as “legacy channel accessparameters,” and the second channel access parameters are sometimesreferred to herein as “non-legacy channel access parameters.”

For example, in an embodiment, the legacy channel access parametersgenerally give the non-legacy client station a same chance of gainingaccess to the communication channel as a legacy client station. In oneor more embodiments, the legacy client stations use only the legacychannel access parameters to gain access to the communication channel,while the client stations configured to operate according to the firstcommunication protocol use the legacy channel access parameters or thenon-legacy channel access parameters depending on a current situation.

In an embodiment, the non-legacy channel access parameters give theclient station con configured to operate according to the firstcommunication protocol a smaller chance of gaining access to thecommunication channel as compared to the legacy client station. Forexample, in an embodiment, the non-legacy channel access parametersinclude a larger CW_(min) as compared to the legacy channel accessparameters. In one or more other embodiments, the chance of gainingaccess to the communication channel differs between the non-legacyclient station and the legacy client station in various other waysdepending on whether the first channel access parameters or the secondchannel access parameters are used.

In an embodiment, a non-legacy client station initially uses the legacychannel access parameters to gain access to the communication channelfollowing association establishment with an AP. For example, in anembodiment, upon receiving an association response frame that the APtransmits to the non-legacy client station during associationestablishment with the non-legacy client station, the non-legacy clientstation uses the legacy channel access parameters to initiate one ormore transmissions of one or more UL SU data units.

In an embodiment, the non-legacy client station continues using thelegacy channel access parameters until the non-legacy client stationsuccessfully completes a trigger-based UL transmission as part of an ULMU transmission. In such an embodiment, if the non-legacy client stationreceives an acknowledgement (ACK) frame from the AP acknowledgingreceipt of the UL data unit transmitted by the non-legacy client stationin response to receiving a trigger frame, the non-legacy client stationthen begins using the non-legacy channel access parameters forsubsequently gaining access to the communication channel. In anembodiment, the non-legacy channel access parameters include a largerCW_(min) as compared to a CW_(min) included in the legacy channel accessparameters.

In an embodiment, the non-legacy client station uses the non-legacychannel access parameters for a pre-determined period of time (e.g.,following the receipt at the client station of the ACK frame from the APacknowledging receipt of the UL data unit transmitted by the clientstation in response to the trigger frame from the AP). For example, inan embodiment, upon reception at the client station of the ACK framefrom the AP, the client station activates (e.g., starts, initiates,etc.) a timer (e.g., a counter clocked at a fixed rate, etc.) to definea period of time during which the client station is to use thenon-legacy channel access parameters for gaining access to thecommunication channel. In an embodiment, upon reception at the clientstation of the ACK frame from the AP, one or more timers (e.g.,counters) are activated for defining respective periods of time duringwhich the client station is to use the non-legacy channel accessparameters for gaining access to the communication channel, where eachtimer corresponds to a respective access category (e.g., a prioritylevel in enhanced distributed channel access (EDCA)) for accessing thechannel. In some embodiments, each timer corresponds to a differentaccess category, a different traffic class, a different priority level,etc.

In accordance with some embodiments, the period of time during which anon-legacy client station configured to operate according to the firstcommunication protocol is to use the non-legacy channel accessparameters is based on an indication transmitted to the non-legacystation by the AP. For example, in an embodiment, the client stationreceives from the AP an indication of the period of time during whichthe client station is to use the non-legacy channel access parameters.In an embodiment, the AP indicates the period of time to the clientstation during association establishment (e.g., the AP includes anindication of the period of time in an association response frame). Insome embodiments, the period of time during which the client stationconfigured to operate according to the first communication protocol isto use the non-legacy channel access parameters is updated by the AP,for example, each beacon interval, according to an embodiment. In someembodiments, the AP includes an indication of the period of time in abeacon frame. In some embodiments, the AP includes an indication of theperiod of time in another suitable frame transmitted to the non-legacyclient station, such as a control frame, a management frame, etc.

FIG. 3 is a block diagram of an example transmission sequence 600 in aWLAN, such as the example WLAN 10 shown in FIG. 1, in which a non-legacyclient station (STA1) utilizes dynamic channel access parameters foruplink transmissions, according to an embodiment. In the examplescenario illustrated in FIG. 3, the WLAN includes an AP, the non-legacySTA1, a non-legacy STA2, and a legacy STA3.

In an embodiment, the non-legacy STA1 (e.g., the client station 25-1 inthe example network 10 shown in FIG. 1) and the non-legacy STA2 (e.g.,the client station 25-2 in FIG. 1) are client stations configured tooperate according to the first communication protocol. In an embodiment,the legacy STA3 (e.g., the client station 25-4 in the example network 10shown in FIG. 1) is a client station configured to operate according toa legacy communication protocol, but is not configured to operateaccording to the first communication protocol.

The AP transmits a trigger frame 604 to prompt an UL MU transmissionfrom a group of client stations that includes the non-legacy STA1 andthe non-legacy STA2. In response to receiving the trigger frame 604, thenon-legacy STA1 transmits 608-1 as part of the UL MU transmission, andthe non-legacy STA2 transmits 608-2 as part of the UL MU transmission.In the scenario illustrated in FIG. 3, the AP successfully receives theUL MU transmission 608 and, in response, transmits an acknowledgment(ACK) 612. At a time t1, the non-legacy STA1 determines that the APsuccessfully received the transmission 608-1 based on the non-legacy STAreceiving the ACK 612 from the AP.

In the example scenario of FIG. 3, the non-legacy STA1 uses legacychannel access parameters during a time period prior to and up to timet1 for gaining access to the channel medium for UL SU transmissions. Forinstance, in one illustrative example, the transmission 608-1 was thefirst successful UL MU transmission by the non-legacy STA1 since thenon-legacy STA1 became associated with the AP, and the non-legacy STA1has been using the legacy channel access parameters since becomingassociated with the AP. As another illustrative example, the non-legacySTA1 had earlier used non-legacy channel access parameters but hadswitched to using legacy channel access parameters, and the transmission608-1 was the first successful UL MU transmission by the non-legacy STA1since the non-legacy STA1 switched to using legacy channel accessparameters.

In response to determining, at time t1, that the AP successfullyreceived the transmission 608-1, the non-legacy STA1 begins usingnon-legacy channel access parameters. Also in response to determining,at time t1, that the AP successfully received the transmission 608-1,and/or in response to beginning use of the non-legacy channel accessparameters, the non-legacy STA1 starts a counter for measuring a timeperiod 620 in which the non-legacy STA1 is to use the non-legacy channelaccess parameters. In an embodiment, the timer (e.g., counter) isinitialized with an initial value corresponding to the time period 620,and the counter counts down from the initial value to zero. In anotherembodiment, the timer is initialized with a predetermined value such aszero, and the counter counts up until it reaches an ending valuecorresponding to a sum of the predetermined value and a valuecorresponding to the time period 620. In another embodiment, an initialvalue of the timer corresponding to time t1 is recorded, and the countercounts up until it reaches an ending value corresponding to a sum of theinitial value and a value corresponding to the time period 620. Inanother embodiment, an initial value of the timer corresponding to timet1 is recorded, and the counter counts down until it reaches an endingvalue corresponding to the initial value minus a value corresponding tothe time period 620. In some embodiments, the non-legacy STA1 maintainsmultiple counters for measuring respective time periods 620 in which thenon-legacy STA1 is to use the non-legacy channel access parameters,where the respective time periods 620 correspond to different accesscategories, traffic classes, priority levels, etc.

On the other hand, the legacy STA3 uses the legacy channel accessparameters. As discussed above, uses of the legacy channel accessparameters, as compared to use of the non-legacy channel accessparameters, tends to provide a greater probability of acquiring accessto the channel medium. Thus, in the illustrative example of FIG. 3, thelegacy STA3 acquires access to the channel medium prior to thenon-legacy STA, which is using the non-legacy channel access parameters.Upon the legacy STA3 acquiring access to the channel medium, the legacySTA3 transmits an UL SU frame 630.

At a time t2, the non-legacy STA1 determines that the counter reached anend value corresponding to expiration of the time period 620. Inresponse, the non-legacy STA1 switches to using the legacy channelaccess parameters. The non-legacy STA1 then acquires access to thechannel medium, using the legacy channel access parameters, and uponacquiring access to the channel medium, the legacy STA3 transmits an ULSU frame 634.

FIG. 4 is a flow diagram of an example method 900 for communicating in acommunication channel of a wireless communication network, in accordancewith one or more embodiments. In some embodiments, the example method900 is implemented by a client station (e.g., client station 25-1 asshown in FIG. 1). As an example, the network interface device 27 isconfigured to implement the method 900, according to some embodiments.For example, in one such embodiment, the MAC processing unit 28 isconfigured to implement at least a portion of the method 900. As anotherexample, the MAC processor 28 is configured to implement a first portionof the method 900, and the PHY processor 29 is configured to implement asecond portion of the method 900, according to an embodiment. In otherembodiments, the method 900 is implemented by other suitable networkinterface devices.

At block 905, a communication device determines, in connection with aprior UL MU communication in which the communication deviceparticipated, whether the communication device is to use i) one or morefirst channel access parameters or ii) one or more second channel accessparameters for accessing a communication medium for a single user (SU)transmission by the communication device. In an embodiment, the one ormore first channel access parameters include one or more legacy channelaccess parameters such as discussed above. In an embodiment, the one ormore second channel access parameters include one or more non-legacychannel access parameters such as discussed above. In an embodiment,using the one or more first channel access parameters are associatedwith a greater probability of obtaining access to the communicationmedium as compared to using the one or more second channel accessparameters.

In an embodiment, block 905 is implemented by a MAC processor such asthe MAC processor 28. In an embodiment, block 905 is implemented by alogic circuit such as the logic circuit 50.

In an embodiment, block 905 comprises using a counter, such as thecounter 54 (FIG. 1), to determine whether a time period has expired. Inan embodiment, block 905 comprises determining whether a transmission bythe communication device as part of the prior UL MU communication wassuccessful. In an embodiment, determining whether the transmission bythe communication device as part of the prior UL MU communication wassuccessful includes determining whether the communication devicereceived an ACK responsive to the transmission by the communicationdevice as part of the prior UL MU communication.

At block 910, the communication device uses the one or more firstchannel access parameters to attempt to access the communication mediumin response to determining, at block 905, that the communication deviceis to use the one or more first channel access parameters.

At block 915, the communication device uses the one or more secondchannel access parameters to attempt to access the communication mediumin response to determining, at block 905, that the communication deviceis to use the one or more second channel access parameters.

In an embodiment, blocks 910 and 915 are implemented by a MAC processorsuch as the MAC processor 28.

At block 920, the communication device transmits an SU transmission viathe communication medium in response to accessing the communicationmedium via either block 910 or 915. In an embodiment, block 920 includesa MAC processor, such as the MAC processor 28, prompting a PHYprocessor, such as the PHY processor 29, to provide one or more basebandsignals to one or more RF circuits, the one or more baseband signalscorresponding to the SU transmission. In an embodiment, block 920includes one or more RF circuits providing one or more RF signals to oneor more antennas, the one or more RF signals corresponding to the SUtransmission.

FIG. 5 is a flow diagram of an example method 1000 for determining, inconnection with a prior UL MU communication in which the communicationdevice participated, whether the communication device is to use i) oneor more first channel access parameters or ii) one or more secondchannel access parameters for accessing a communication medium for a SUtransmission by the communication device, in accordance with one or moreembodiments. In some embodiments, the example method 1000 is implementedby a client station (e.g., client station 25-1 as shown in FIG. 1). Asan example, the network interface device 27 is configured to implementthe method 1000, according to some embodiments. For example, in one suchembodiment, the MAC processing unit 28 is configured to implement atleast a portion of the method 1000. In one embodiment, the logic circuit50 is configured to implement at least a portion of the method 1000.

Referring now to FIGS. 4 and 5, in an embodiment, block 905 includes themethod 1000. In other embodiments, however, block 905 includes anothersuitable method.

In an embodiment, the method 1000 is performed in connection with acommunication device having participated in a prior UL MU communication.

At block 1005, the communication device determines whether atransmission by the communication device, as part of the prior UL MUcommunication, was successful. In an embodiment, block 1005 includesdetermining whether the communication device received an ACK fromanother communication device (e.g., an AP) responsive to thetransmission by the communication device as part of the prior UL MUcommunication. For example, in an embodiment, receipt of the ACKindicates that the transmission was successful, whereas if an ACK is notreceived within a predetermined time after the transmission wascompleted, this may indicate that the transmission was not successful.In some embodiments, when block ACKs are utilized, a client device maynot determine whether a transmission was successful until after havingparticipated in multiple UL MU communications.

If it is determined at block 1005 that the transmission was successful,the flow proceeds to block 1010. At block 1010, the communication devicedetermines that the communication device is to use the one or moresecond channel access parameters.

On the other hand, if it is determined at block 1005 that thetransmission was not successful, the flow proceeds to block 1015. Atblock 1015, the communication device determines that the communicationdevice is to use the one or more first channel access parameters. Forexample, in an embodiment, the communication device determines whetheri) to set a new backoff counter according to the one or more firstchannel access parameters, or ii) to resume the existing backoffcounter; then starts the new backoff counter or resumes the existingbackoff counter. In an embodiment, the communication device sets a newbackoff counter according to the one or more first channel accessparameters in response to determining (at block 1005) that thetransmission was not successful. In an embodiment, the communicationdevice resumes the existing backoff counter in response to determining(at block 1005) that the transmission was not successful.

FIG. 6 is a flow diagram of an example method 1100 for determiningwhether a communication device is to use i) one or more first channelaccess parameters or ii) one or more second channel access parametersfor accessing a communication medium for a SU transmission by thecommunication device, in accordance with one or more embodiments. Insome embodiments, the example method 1100 is implemented by a clientstation (e.g., client station 25-1 as shown in FIG. 1). As an example,the network interface device 27 is configured to implement the method1100, according to some embodiments. For example, in one suchembodiment, the MAC processing unit 28 is configured to implement atleast a portion of the method 1100. In one embodiment, the logic circuit50 is configured to implement at least a portion of the method 1100.

Referring now to FIGS. 4 and 6, in an embodiment, block 905 includes themethod 1100. In other embodiments, however, block 905 includes anothersuitable method.

Referring now to FIGS. 4-6, in an embodiment, block 905 includes themethod 1000 and also includes the method 1100. In other embodiments,however, block 905 includes only one of, or neither of, the method 1000and the method 1100.

In an embodiment, the method 1100 is performed in connection with acommunication device having successfully completed a transmission aspart of a prior UL MU communication. In an embodiment, the method 1100is performed in connection with a communication device having determinedto use the one or more second channel access parameters. In anembodiment, the method 1100 is performed in connection with acommunication device having determined to use the one or more secondchannel access parameters in response to determining that communicationdevice successfully completed a transmission as part of a prior UL MUcommunication.

At block 1105, the communication device starts a counter. In anembodiment, the communication device starts a counter in connection withone or both of i) determining that communication device successfullycompleted a transmission as part of a prior UL MU communication, and ii)determining that the communication device is to use the one or moresecond channel access parameters. In an embodiment, the logic circuit 50starts the counter 54.

In an embodiment, block 1105 includes causing the counter to beginincrementing. In an embodiment, block 1105 includes causing the counterto begin decrementing.

In an embodiment, block 1105 includes setting an initial value of thecounter to a value corresponding to a time period to be measured,wherein the time period corresponds to a time period in which thecommunication device is to use the one or more second channel accessparameters. In an embodiment, block 1105 includes setting an initialvalue of the counter to zero or another suitable initial value. In anembodiment, block 1105 includes recording an initial value of thecounter.

At block 1110, it is determined whether the counter reached an end valuecorresponding to the time period having expired. In an embodiment, block1110 is repeated until it is determined that the counter reached the endvalue. In response to determining that the counter reached the endvalue, the flow proceeds to block 1115. At block 1115, the communicationdevice determines that the communication device is to use the one ormore first channel access parameters.

At least some of the various blocks, operations, and techniquesdescribed above may be implemented utilizing hardware, a processorexecuting firmware instructions, a processor executing softwareinstructions, or any combination thereof. When implemented utilizing aprocessor executing software or firmware instructions, the software orfirmware instructions may be stored in any computer readable memory suchas on a magnetic disk, an optical disk, or other storage medium, in aRAM or ROM or flash memory, processor, hard disk drive, optical diskdrive, tape drive, etc. The software or firmware instructions mayinclude machine readable instructions that, when executed by one or moreprocessors, cause the one or more processors to perform various acts.

When implemented in hardware, the hardware may comprise one or more ofdiscrete components, an integrated circuit, an application-specificintegrated circuit (ASIC), a programmable logic device (PLD), etc.

While the present invention has been described with reference tospecific examples, which are intended to be illustrative only and not tobe limiting of the invention, changes, additions and/or deletions may bemade to the disclosed embodiments without departing from the scope ofthe invention.

What is claimed is:
 1. A method for communicating in a communicationnetwork, the method comprising: determining, at a communication deviceand in connection with a prior uplink multi-user (UL MU) communicationin which the communication device participated, whether thecommunication device is to use i) one or more first channel accessparameters or ii) one or more second channel access parameters foraccessing a communication medium for a single user (SU) transmission bythe communication device, wherein using the one or more first channelaccess parameters is associated with a greater probability of obtainingaccess to the communication medium as compared to using the one or moresecond channel access parameters; in response to determining that thecommunication device is to use the one or more first channel accessparameters, using, at the communication device, the one or more firstchannel access parameters to attempt to access the communication medium;in response to determining that the communication device is to use theone or more second channel access parameters, using, at thecommunication device, the one or more second channel access parametersto attempt to access the communication medium; and in response toaccessing the communication medium, transmitting, with the communicationdevice, the SU transmission via the communication medium.
 2. The methodof claim 1, wherein determining whether the communication device is touse i) the one or more first channel access parameters, or ii) the oneor more second channel access parameters includes: using, at thecommunication device, a counter to measure a time period associated withthe prior UL MU communication in which the communication deviceparticipated; responsive to determining, using the counter, that thetime period has not expired, determining that the first communicationdevice is to use the one or more second channel access parameters; andresponsive to determining, using the counter, that the time period hasexpired, determining that the first communication device is to use theone or more first channel access parameters associated with the greaterprobability of obtaining access to the communication medium as comparedto using the one or more second channel access parameters.
 3. The methodof claim 2, further comprising: receiving, at the communication device,a time value parameter from an access point device that manages thecommunication network, wherein the time value parameter indicates thetime period; and using, at the communication device, the time valueparameter received from the access point device to determine the timeperiod.
 4. The method of claim 1, wherein determining whether thecommunication device is to use i) the one or more first channel accessparameters, or ii) the one or more second channel access parametersincludes: determining, at the communication device, whether atransmission by the communication device as part of the prior UL MUcommunication was successful; responsive to determining that thetransmission by the communication device as part of the prior UL MUcommunication was successful, determining, at the communication device,that the communication device is to use the one or more second channelaccess parameters; and responsive to determining that the transmissionby the communication device as part of the prior UL MU communication wasnot successful, determining, at the communication device, that thecommunication device is to use the one or more first channel accessparameters associated with the greater probability of obtaining accessto the communication medium as compared to using the one or more secondchannel access parameters.
 5. The method of claim 4, wherein determiningwhether the transmission by the communication device as part of theprior UL MU communication was successful includes: determining, at thecommunication device, whether the communication device received anacknowledgment from another communication device in response to thetransmission by the communication device as part of the prior UL MUcommunication.
 6. The method of claim 1, further comprising:associating, at the communication device, with an access point devicethat manages the communication network; and in response to becomingassociated with the access point device, using, at the communicationdevice, the one or more first channel access parameters to attempt toaccess the communication medium.
 7. The method of claim 6, wherein:using, in response to becoming associated with the access point device,the one or more first channel access parameters to attempt to access thecommunication medium comprises: using the one or more first channelaccess parameters to attempt to access the communication medium untildetermining, at the communication device, that the communication devicesuccessfully completed a transmission as part of an UL MU communication;and determining, in connection with the prior UL MU communication inwhich the communication device participated, whether the communicationdevice is to use i) the one or more first channel access parameters, orii) the one or more second channel access parameters includes: inresponse to determining that the communication device successfullycompleted the transmission as part of the UL MU communication,determining that the communication device is to use the one or moresecond channel access parameters for accessing the communication medium.8. The method of claim 7, wherein: determining, in connection with theprior UL MU communication in which the communication deviceparticipated, whether the communication device is to use i) the one ormore first channel access parameters, or ii) the one or more secondchannel access parameters includes: in response to determining that thecommunication device did not successfully complete a transmission aspart of the UL MU communication, determining that the communicationdevice is to use the one or more first channel access parameters foraccessing the communication medium.
 9. The method of claim 1, wherein:the one or more first channel access parameters includes a firstcontention window minimum size; and the one or more second channelaccess parameters includes a second contention window minimum size thatis different than the first contention window minimum size.
 10. Themethod of claim 9, wherein the second contention window minimum size islarger than the first contention window minimum size.
 11. An apparatus,comprising: a network interface device associated with a communicationdevice, the network interface device having one or more integratedcircuit devices, wherein the network interface device comprises: a mediaaccess control (MAC) processor implemented on the one or more integratedcircuit devices, wherein the MAC processor includes: a logic circuitimplemented on the one or more integrated circuit devices, the logiccircuit configured to: determine, in connection with a prior uplinkmulti-user (UL MU) communication in which the communication deviceparticipated, whether the network interface device is to use i) one ormore first channel access parameters or ii) one or more second channelaccess parameters for accessing a communication medium for a single user(SU) transmission by the communication device, wherein using the one ormore first channel access parameters is associated with a greaterprobability of obtaining access to the communication medium as comparedto using the one or more second channel access parameters; wherein theone or more integrated circuit devices are configured to: in response todetermining that the communication device is to use the one or morefirst channel access parameters, use the one or more first channelaccess parameters to attempt to access the communication medium, inresponse to determining that the communication device is to use the oneor more second channel access parameters, use the one or more secondchannel access parameters to attempt to access the communication medium,and in response to accessing the communication medium, prompt thecommunication device to transmit the SU transmission via thecommunication medium.
 12. The apparatus of claim 11, wherein: the logiccircuit includes a counter circuit; and the logic circuit is configuredto: use the counter circuit to measure a time period associated with theprior UL MU communication in which the communication deviceparticipated, responsive to determining, using the counter circuit, thatthe time period has not expired, determine that the communication deviceis to use the one or more second channel access parameters, andresponsive to determining, using the counter circuit, that the timeperiod has expired, determine that the communication device is to usethe one or more first channel access parameters associated with thegreater probability of obtaining access to the communication medium ascompared to using the one or more second channel access parameters. 13.The apparatus of 12, wherein: the one or more the network interfacedevice is configured to receive a time value parameter from an accesspoint device that manages the communication network, wherein the timevalue parameter indicates the time period; and the logic circuit isconfigured to use the time value parameter received from the accesspoint device to determine the time period.
 14. The apparatus of claim11, wherein the logic circuit is configured to: determine whether atransmission by the communication device as part of the prior UL MUcommunication was successful; responsive to determining that thetransmission by the communication device as part of the prior UL MUcommunication was successful, determine that the network interfacedevice is to use the one or more second channel access parameters; andresponsive to determining that the transmission by the communicationdevice as part of the prior UL MU communication was not successful,determine that the network interface device is to use the one or morefirst channel access parameters associated with the greater probabilityof obtaining access to the communication medium as compared to using theone or more second channel access parameters.
 15. The apparatus of claim14, wherein the logic circuit is configured to: determine whether thecommunication device received an acknowledgment from anothercommunication device in response to the transmission by thecommunication device as part of the prior UL MU communication; anddetermine whether the transmission by the communication device as partof the prior UL MU communication was successful based on whether thecommunication device received the acknowledgment.
 16. The apparatus ofclaim 11, wherein the network interface device is configured to:associate with an access point device that manages a communicationnetwork; and in response to the network interface device becomingassociated with the access point device, use the one or more firstchannel access parameters to attempt to access the communication medium.17. The apparatus of claim 16, wherein: the network interface device isconfigured to, in response to the network interface device becomingassociated with the access point device, use the one or more firstchannel access parameters to attempt to access the communication mediumuntil determining that the communication device successfully completed atransmission as part of an UL MU communication; and the logic circuit isconfigured to: in response to determining that the communication devicesuccessfully completed the transmission as part of the UL MUcommunication, determine that the network interface device is to use theone or more second channel access parameters for accessing thecommunication medium.
 18. The apparatus of claim 17, wherein the logiccircuit is configured to: in response to determining that thecommunication device did not successfully complete a transmission aspart of the UL MU communication, determine that the communication deviceis to use the one or more first channel access parameters for accessingthe communication medium.
 19. The apparatus of claim 11, wherein thelogic circuit comprises a hardware state machine.
 20. The apparatus ofclaim 19, wherein the network interface device comprises: a tangible,non-transitory memory storing machine instructions; and a processorcoupled to the memory, the processor configured to execute machineinstructions stored in the memory; wherein the logic circuit isimplemented using the processor executing machine instructions stored inthe memory.